Signal processing under attenuated transmission conditions

ABSTRACT

Signal processing under attenuated transmission conditions. Within an orthogonal signal space, the number of orthogonal signals that are used to transmit information from a transmitter to a receiver is reduced and the transmitted power of each of the now remaining orthogonal signals is modified; this may involve increasing the power of all of the remaining orthogonal signals equally or alternatively modifying them individually. The same modulation used before the reduction may also be used afterwards; within communication systems having multiple transmitter-receiver paths, this will ensure that the communication system&#39;s throughput and efficiency will remain unchanged even when one (or more) transmitter-receiver paths are highly attenuated. In addition, robust mode operation is provided for ranging and registering of transmitter devices when entering the communication system. In addition, the unused orthogonal signals may be employed to support interference cancellation of those orthogonal signals that are used to transmit information.

CROSS REFERENCE TO RELATED PATENTS/PATENT APPLICATIONS ContinuationPriority Claim, 35 U.S.C. §120

The present U.S. Utility patent application claims priority pursuant to35 U.S.C. §120, as a continuation, to the following U.S. Utility patentapplication which is hereby incorporated herein by reference in itsentirety and made part of the present U.S. Utility patent applicationfor all purposes:

1. U.S. Utility application Ser. No. 10/427,593, entitled “Signalprocessing under attenuated transmission conditions,” filed May 1, 2003,pending, and scheduled to be issued as U.S. Pat. No. 7,529,289 on May 5,2009, which claims priority pursuant to 35 U.S.C. §119(e) to thefollowing U.S. Provisional patent application which is herebyincorporated herein by reference in its entirety and made part of thepresent U.S. Utility patent application for all purposes:

a. U.S. Provisional Application Ser. No. 60/416,889, entitled “Signalprocessing under attenuated transmission conditions,” filed Oct. 8,2002, now expired.

The U.S. Utility application Ser. No. 10/427,593 also claims prioritypursuant to 35 U.S.C. §120, as a continuation-in-part (CIP), to thefollowing U.S. Utility patent application which is hereby incorporatedherein by reference in its entirety and made part of the present U.S.Utility patent application for all purposes:

1. U.S. Utility application Ser. No. 09/652,721, entitled“Subdimensional single carrier modulation,” filed Aug. 31, 2000, nowU.S. Pat. No. 6,778,611, issued Aug. 17, 2004, which claims prioritypursuant to 35 U.S.C. §119(e) to the following U.S. Provisional patentapplication:

a. U.S. Provisional Application Ser. No. 60/151,680, entitled“Subdimensional single carrier modulation,” filed Aug. 31, 1999, nowexpired.

The U.S. Utility application Ser. No. 10/427,593 also claims prioritypursuant to 35 U.S.C. §120, as a continuation-in-part (CIP), to thefollowing U.S. Utility patent application which is hereby incorporatedherein by reference in its entirety and made part of the present U.S.Utility patent application for all purposes:

1. U.S. Utility application Ser. No. 10/142,189, entitled “Cancellationof interference in a communication system with application to S-CDMA,”filed May 8, 2002, now U.S. Pat. No. 7,110,434, issued Sep. 19, 2006,which claims priority pursuant to 35 U.S.C. §119(e) to the followingU.S. Provisional patent application:

a. U.S. Provisional Application Ser. No. 60/367,564, entitled“Cancellation of interference in a communication system with applicationto S-CDMA,” filed Mar. 26, 2002, now expired.

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

The invention relates generally to communication systems; and, moreparticularly, it relates to communication systems that operate underattenuated transmission conditions.

2. Description of Related Art

The problems presented by attenuation of transmitted signals withincommunication systems have existed for quite some time. In manydifferent types of communication systems, there may be an undesirableattenuation of a signal when being transmitted from a transmitter to areceiver through the infrastructure of the communication system. That isto say, a transmitter may experience a large attenuation of itstransmitted signals when they travel to the receiver via thecommunication system.

In one type of communication system, a cable modem communication system,this path may be viewed as being an upstream or reverse path between aCable Modem (CM) and a Cable Modem Termination System (CMTS), and/or theforward path of communication from the CMTS to any one or more CMswithin the cable modem communication system.

In addition, within many communication system networks, there are amultitude of transmitter-to-receiver paths between the various devices,and there is a large variety of degrees of attenuation among all ofthose various paths. Some paths may have large attenuation, and some maynot have so large an attenuation; there is a continuum of possibledegrees of attenuation throughout the various paths within thecommunication system.

Referring back to the cable modem communication system (which issometimes referred to as a cable plant), the Data Over Cable ServiceInterface Specification (DOCSIS) will typically govern the transmissionand receipt of signals throughout the cable modem communication system.In this situation, some cable modems (CMs) may have greater attenuationthan others over the transmission paths from their respective CM outputto the cable headend (e.g., the CMTS contained therein). As a furtherexample, in an apartment complex, there may be long runs of cable,including one or more splitters, connecting the various apartment units.Thus, the cabling itself from the CM may itself even introduce a largeattenuation even before that particular CM cabling, within the apartmentbuilding, is attached to the rest of the cable plant.

These same effects may also be present within wireless communicationsystems. For example, within a wireless transmission path, where pathlength differences between the various devices within the system mayvary greatly, with some transmitter-receivers being located relativelyclose and perhaps within a line-of-sight of a wireless terminationsystem, while other transmitter-receivers may be located at a greatdistance from the wireless termination system and perhaps have anobscured line-of-sight and/or destructively interfering multipath.

While there are some prior art approaches to deal with the problemspresented by undesirable attenuation of signals as they are transmittedthrough the communication system, these prior art approaches fail toaddress this large attenuation within the transmission path without alsodegrading the efficient operation for the full set of transmittersoperating into a given receiver. For example, in the cable modemcommunication system context, these prior art approaches will themselvesoftentimes introduce degradation of some, if not all, of the CMs as theytransmit signals to the CMTS. In addition, these prior art approacheswill typically significantly increase the complexity of thecommunication system's components. This increase in the complexity ofthe communication system's components, provided by the prior artapproaches, is typically found in increases to the complexity of theMedia Access Control (MAC) (sometimes referred to as the Medium AccessControl) and Physical (PHY) layer components of the communicationsystem.

One prior art means for satisfying the problem of one (or several) ofthe many transmitter-receiver links suffering excessive attenuation (orpath loss) is to employ a receiver having certain flexibility in itsoperating characteristics. Such a flexible receiver would be capable ofoperating at a multitude of SNRs (Signal to Noise Ratios) in the networkenvironment. The flexible receiver quickly adjusts from high SNRreception to low SNR reception and/or vice-versa, and it would utilize aMAC layer which efficiently manipulates and allocates access to thenetwork while factoring in the variation throughput which necessarilyaccompanies the variety of SNRs across the various links within thecommunication system. These system level concepts have been proposed forthis problem already in the prior art, especially in the wirelessenvironment, under the moniker of multi-channel multipoint distributionservice (MMDS) Adaptive Modulation approach. However, a major drawbackof many such Adaptive Modulation approaches is the typically immensecomplexity associated therewith, especially, but not solely, whenresolving the MAC layer issues.

In addition, within many communication systems, there is a requirementthat all transmitters be constrained to use the same modulationparameters. This may be because the receiver is limited to receivingsignals using that common set of modulation parameters orcharacteristics. As mentioned above, the prior art approach of providingsuch rapidly changing receiver flexibility at the PHY layer and at theMAC layer is not without a significant increase in complexity. Theseparameters may include the modulation order (QPSK (Quadrature PhaseShift Keying), 16 QAM (Quadrature Amplitude Modulation), 64 QAM, etc.),the FEC (Forward Error Correction) parameters (RS (Reed Solomon)codeword length N and number of correctable bytes T), and otherparameters as well.

In a communication system lacking such an extremely sophisticated andflexible PHY and MAC layer, if one of the transmitters is disadvantagedand unable to communicate using the particular modulation order at hand,such as 64 QAM, then this would cause a reduction of the modulationorder on the entire channel to a lower order prescribed modulation thatall of the transmitters can accommodate. For example, this could involvereducing the modulation order from 64 QAM to 32 QAM, in one instance, orto an even lower modulation order as dictated by the highly attenuatedand problematic transmitter-receiver path. Therefore, in doing so, allof the transmitters need to be reduced to the lower order modulation; itwould require reducing all of the transmitters to 32 QAM in thisexample. This would undesirably reduce the raw throughput of thecommunication channel (bits per second) by a ratio of 5/6. Clearly,there are situations where the reduction of modulation order may be evenmore significant and the throughput of the communication channel wouldbe even more affected.

Another problem that often arises in such communication systems is anupper limit on the power that a particular transmitter is capable ofusing, or is permitted to use, to transmit its information. Such anupper power limit may be imposed by the capabilities of economicallyimplemented transmit amplifiers which are allocated to have a certainmaximum transmit power given a spurious fidelity requirement that mustbe met. In addition, the regulatory agencies (e.g., the FederalCommunications Commission (FCC)) may also impose a limit on transmitpower to prevent interference with other services operating within otherfrequency spectra. In addition, in some systems, there is a nonlinearelement in the communication channel which limits the power that can bepassed through the communication channel. In the case of a cable modemcommunication system, one potential source of nonlinearity may be anupstream laser which will clips signals above a certain maximum powerlevel.

One prior art approach that seeks to deal with these deficiencies is toincrease the transmitted power of a transmitter up to a certain point soas to overcome the high attenuation of its transmitter-receivertransmission path. However, because of the inherent limitations of thedevice, the transmitter can not increase its power beyond an upper limitpoint, as described above. Again, this upper transmitted power limitcould be due to standards, wherein the limitations are attempting toallow coexistence with other communications networks or broadcasts, suchas wireless systems. Alternatively, the upper transmitted power limitmay be caused by agreed-upon practical or cost-effective limits (as inDOCSIS), or they could be a combination of these factors. This powerlimitation, regardless of which source introduces it, inherentlypresents a limit by which this prior art approach can employ theincreasing of transmitted power to address this problem.

Yet another problem that arises in such communication system is aproblem associated with the multipoint-to-point connectivity withincommunication systems. A transmitter may need to enter the network(e.g., range and register) before it can communicate in a normal mannerwithin the communication system. The attenuated transmission conditionsmay simply make prior art approaches to perform this ranging andregistering impossible, given the oftentimes relatively low SNR on thecommunication channel of interest on which the ranging and registeringis to be performed.

Also along these lines of a communication system having a communicationchannel that is extremely attenuated, in many multipoint-to-pointcommunication systems, a headend receiver (e.g., a CMTS of a cableheadend in a cable modem communication system) must adjust thetransmission parameters of the transmitters (e.g., the CMs in a cablemodem communication system) based on transmissions (such as rangingbursts) from the transmitters to the receiver. That is, the transmittermust send a ranging burst to the receiver, and the receiver must makemeasurements on the ranging burst and determine adjustments, if any, toone or more of the transmitter's operational parameters. Thesetransmitter operational parameters may include timing offset, frequencyoffset, power, equalizer coefficients, among other parameters. However,in an attenuated channel, the ranging burst itself is likely to have asignificantly reduced SNR upon arrival at the receiver. This will againmake the ranging and registering of the transmitter challenging. Even ifthe ranging and registering of the transmitter may be performed, it islikely to be made with significant error given the significantly reducedSNR of the ranging burst upon arrival at the receiver.

Therefore, there does not presently exist, in the art, a means by whicha transmitter can overcome a severe attenuation in its transmission pathto the receiver and thereby maintain reliable operation at the receiver.As such, no prior art solution is able to address the even morecomplicated situation that arises within multipoint-to-pointcommunication systems having numerous reflections, additional paths,etc. contained throughout the communication system.

In addition, the prior art does not presently provide a solution bywhich a transmitter can overcome a severe attenuation in its path to thereceiver and still maintain a desired SNR at the receiver. The prior artalso presents no solution by which a transmitter can increase the SNR atthe receiver without increasing its transmitted signal power beyond thecertain/predetermined limit as described above.

There also does not presently exist, in the art, a means by which atransmitter can reduce its own throughput while retaining its assignedmodulation parameters, and hence not require the other transmitters onthe communication channel to reduce their throughput as well.

BRIEF SUMMARY OF THE INVENTION

The present invention is directed to apparatus and methods of operationthat are further described in the following Brief Description of theSeveral Views of the Drawings, the Detailed Description of theInvention, and the claims. Other features and advantages of the presentinvention will become apparent from the following detailed descriptionof the invention made with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a system diagram illustrating an embodiment of a cable modemcommunication system that is built according to the invention.

FIG. 2 is a system diagram illustrating another embodiment of a cablemodem communication system that is built according to the invention.

FIG. 3 is a system diagram illustrating an embodiment of a satellitecommunication system that is built according to the invention.

FIG. 4 is a system diagram illustrating an embodiment of a HighDefinition Television (HDTV) communication system that is builtaccording to the invention.

FIG. 5A and FIG. 5B are system diagrams illustrating embodiment ofuni-directional cellular communication systems that are built accordingto the invention.

FIG. 5C is a system diagram illustrating embodiment of a bi-directionalcellular communication system that is built according to the invention.

FIG. 6A is a system diagram illustrating embodiment of a uni-directionalmicrowave communication system that is built according to the invention.

FIG. 6B is a system diagram illustrating embodiment of a bi-directionalmicrowave communication system that is built according to the invention.

FIG. 7A is a system diagram illustrating embodiment of a uni-directionalpoint-to-point radio communication system that is built according to theinvention.

FIG. 7B is a system diagram illustrating embodiment of a bi-directionalpoint-to-point radio communication system that is built according to theinvention.

FIG. 8A is a system diagram illustrating embodiment of a uni-directionalcommunication system that is built according to the invention.

FIG. 8B is a system diagram illustrating embodiment of a bi-directionalcommunication system that is built according to the invention.

FIG. 8C is a system diagram illustrating embodiment of a one to manycommunication system that is built according to the invention.

FIG. 9 is a system diagram illustrating an embodiment of a Cable ModemTermination System (CMTS) system that is built according to theinvention.

FIG. 10A is a diagram illustrating logical channel partitioning of aportion of spectrum that is performed according to the invention.

FIG. 10B is a diagram illustrating an embodiment of logical channelpartitioning of Synchronous Code Division Multiple Access (S-CDMA) codesin a Data Over Cable Service Interface Specification (DOCSIS) systemthat is performed according to the invention.

FIG. 11 is a diagram illustrating an alternative embodiment of logicalchannel partitioning of S-CDMA codes in a DOCSIS system that isperformed according to the invention.

FIG. 12 is a functional block diagram illustrating an embodiment ofpower and modulation adaptation functionality that is arranged accordingto the invention

FIG. 13 is a functional block diagram illustrating an embodiment ofranging and registering functionality that is arranged according to theinvention

FIG. 14A is a diagram illustrating example upstream burst profiles thatmay be employed according to the invention.

FIG. 14B is a diagram illustrating example modulation densities that maybe employed according to the invention.

FIG. 15 is an operational flow diagram illustrating an embodiment of anattenuated transmission adaptation method, employing power andmodulation adaptation, that is performed according to the invention.

FIG. 16 is an operational flow diagram illustrating an embodiment of anattenuated transmission adaptation method, employing ranging andregistering adaptation, that is performed according to the invention.

FIG. 17A, FIG. 17B, FIG. 18A, and FIG. 18B are operational flow diagramsillustrating embodiments of attenuated transmission adaptation methodsthat are performed according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

Various aspects of the invention address the many deficiencies of theprior art when dealing with a large attenuation in the path from atransmitter to a receiver. The invention is able to provide, among otherbenefits, a solution that allows optimal use of bandwidth within acommunication system. In the presence of insufficient SNR, a transmittermay reduce its throughput or bits per second, (and thus attempt reliablecommunications) in either of two ways: by reducing its constellationorder, for example, from 64 QAM to QPSK, or by reducing the bandwidth—ornumber of signaling dimensions per time interval—that it employs.

Reducing constellation order (bits per symbol) decreases the SNRrequired at the receiver for reliable communications. However, by doingso, it also reduces the throughput efficiency (bits per second per Hertz(Hz)) of the overall communications channel. This may be problematic, inthat, the PHY operational parameters are typically shared among ALL ofthe transmitters on the same channel. Therefore, this choice, by itself,will provide some improved performance, yet it is not particularlyattractive. The other option of reducing the number of signalingdimensions per time interval—for the transmitters with insufficient SNRin “normal” operation—remains. Reducing the number of signalingdimensions allocated per time interval for selected transmitters solvesthe insufficient SNR problem but at the expense of reduced channelthroughput.

However, when dealing with the real limitation of maximum possibletransmit power of a device (the limitation may be caused by a variety ofreasons, some of which are described above), it is found that reducingthe number of signaling dimensions combined with keeping the transmitpower at a maximum (in one embodiment), does in fact increase the SNRper dimension (or per symbol) at the receiver. In addition, otherembodiments of the invention envision reducing the number of signalingdimensions combined with intelligently modifying the transmit power inan effort to increase the SNR per dimension (or per symbol) at thereceiver.

Therefore, the appropriate reduction in the number of allocatedsignaling dimensions for a disadvantaged transmitter, while modifyingthe allowed transmit power (setting it to a maximum in one embodiment),provides that the SNR per dimension at the receiver can be brought up tothe level achieved by the more typical transmitters within thecommunication system whose transmitter-receiver links are notdisadvantaged by severe attenuation.

Therefore, this combination technique provides a solution for many ofthe deficiencies described above, namely, by ensuring that a similar SNRis working into the receiver for all of the transmitters of the system,and that similar PHY layer operational parameters may be employed forall of the transmitters. Hence, the invention provides, among otherbenefits, a means by which a transmitter can maintain the desired SNR atthe receiver while not decreasing the overall throughput or throughputefficiency of the entire communication channel. By maintaining the SNRat the receiver, the difficulties of the flexible PHY receiver areeliminated, and the difficulties of the associated MAC layer are greatlyreduced as well. Other details, benefits, and aspects of the inventionare also described in more detail below.

FIGS. 1, 2, 3, 4, 5A, 5B, 5C, 6A, 6B, 7A, 7B, 8A, 8B, 8C, and 9illustrate a number of communication system context embodiments wherevarious aspects of the invention may be implemented.

FIG. 1 is a system diagram illustrating an embodiment of a cable modemcommunication (CM) system 100 that is built according to the invention.The CM communication system 100 includes a number of CMs that may beused by different users (shown as a CM 1, a CM 2, . . . , and a CM n)and a cable headend that includes a Cable Modem Termination System(CMTS) and a cable headend transmitter. The CMTS is a component thatexchanges digital signals with CMs on a cable network.

Each of the CMs (shown CM 1, CM 2, . . . , and CM n) is operable tocommunicatively couple to a Cable Modem (CM) network segment. A numberof elements may be included within the CM network segment. For example,routers, splitters, couplers, relays, and amplifiers may be containedwithin the CM network segment without departing from the scope andspirit of the invention.

The CM network segment allows communicative coupling between a CMs and acable headend that includes the cable modem headend transmitter and theCMTS. The CMTS may be located at a local office of a cable televisioncompany or at another location within a CM communication system. Thecable headend transmitter is able to provide a number of servicesincluding those of audio, video, local access channels, as well as anyother service known in the art of cable systems. Each of these servicesmay be provided to the one or more CMs (shown as a CM 1, CM 2, . . . ,and CM n).

In addition, through the CMTS, the CMs are able to transmit and receivedata from the Internet and/or any other network to which the CMTS iscommunicatively coupled via an external network connection. Theoperation of a CMTS, at the cable-provider's head-end, may be viewed asproviding analogous functions that are provided by a digital subscriberline access multiplexor (DSLAM) within a digital subscriber line (DSL)system. The CMTS takes the traffic coming in from a group of customerson a single channel and routes it to an Internet Service Provider (ISP)for connection to the Internet, as shown via the external networkconnection that communicatively couples to the Internet access. At thehead-end, the cable providers will have, or lease space for athird-party ISP to have, servers for accounting and logging, dynamichost configuration protocol (DHCP) for assigning and administering theInternet protocol (IP) addresses of all the cable system's users(specifically, the CM 1, CM 2, . . . , and CM n), and typically controlservers for a protocol called Data Over Cable Service InterfaceSpecification (DOCSIS), the major standard used by U.S. cable systems inproviding Internet access to users. The servers may also be controlledfor a protocol called European Data Over Cable Service InterfaceSpecification (EuroDOCSIS), the major standard used by European cablesystems in providing Internet access to users, without departing fromthe scope and spirit of the invention. In addition, a Japanese DOCSISspecification is also currently under development, and the invention isoperable within the Japanese DOCSIS specification as well.

The downstream information flows to any one or more of the connected CMs(shown as the CM 1, CM 2, . . . , and CM n). The individual networkconnection, within the CM network segment, decides whether a particularblock of data is intended for that particular CM or not. On the upstreamside, information is sent from the CMs (shown as the CM 1, CM 2, . . . ,and CM n) to the CMTS; on this upstream transmission, the CMs (shown asthe CM 1, CM 2, . . . , and CM n) to which the data is not intended donot see that data at all.

As an example of the capabilities provided by a CMTS, the CMTS willenable as many as 1,000 users to connect to the Internet through asingle 6 MHz channel. Since a single channel is capable of 30-40 Mbps(mega-bits per second) of total throughput, this means that users maysee far better performance than is available with standard dial-upmodems that may be used to access external networks such as theInternet. Some embodiments implementing the invention are describedbelow and in the various Figures that show the data handling and controlwithin one or both of a CM and a CMTS within a CM system that operatesby employing CDMA (Code Division Multiple Access) and/or S-CDMA(Synchronous Code Division Multiple Access).

The CMs (shown as the CM 1, CM 2, . . . , and CM n) and the CMTScommunicate synchronization information to one another to ensure properalignment of transmission from the CMs to the CMTS. This is where thesynchronization of the S-CDMA communication systems is extremelyimportant. When a number of the CMs all transmit their signals at a sametime such that these signals are received at the CMTS on the samefrequency and at the same time, they must all be able to be properlyde-spread and decoded for proper signal processing.

Each of the CMs (shown as the CM 1, CM 2, . . . , and CM n) is located arespective transmit distance from the CMTS. In order to achieve optimumspreading diversity and orthogonality for the CMs (shown as the CM 1, CM2, . . . , and CM n) when transmitting to the CMTS, each of the CMtransmissions must be synchronized so that it arrives, from theperspective of the CMTS, synchronous with other CM transmissions. Inorder to achieve this goal, for a particular transmission cycle, each ofthe CMs typically transmits to the CMTS at a respective transmissiontime, which will likely differ from the transmission times of other CMs.These differing transmission times will be based upon the relativetransmission distance between the CM and the CMTS. These operations maybe supported by the determination of the round trip delays (RTPs)between the CMTS and each supported CM. With these RTPs determined, theCMs may then determine at what point to transmit their S-CDMA data sothat all CM transmissions will arrive synchronously at the CMTS.

The invention employs attenuated transmission adaptation functionalitywithin one or more of the CMs (shown as the CM 1, CM 2, . . . , and CMn). In some embodiments, the CMTS is able to support CM transmissioninstruction functionality such that the CMTS will direct the CM toperform certain adaptation of the manner in which the CM transmitsinformation upstream to the CMTS; this situation may be viewed as beingan embodiment where the CMTS has access to information (such the Signalto Noise Ratio (SNR) of the communication link from the CM to the CMTS,the cable modem communication system's operating conditions, and/orother information) that it is able intelligently to make such decisionsregarding the manner in which the CM transmits information upstream tothe CMTS. The communication of instructions to and from the CMs and theCMTS may be performed using a variety of means including: 1. via aseparate logical channel through the CM network segment, 2. via aproprietary communication channel via the downstream transmissiondirection from the CMTS to the CMs, and/or 3. via any othercommunication means.

FIG. 2 is a system diagram illustrating another embodiment of a cablemodem communication system 200 that is built according to the invention.From certain perspectives, the FIG. 2 may be viewed as a communicationsystem allowing bi-directional communication between a customer premiseequipment (CPE) and a network. In some embodiments, the CPE is apersonal computer or some other device allowing a user to access anexternal network. The CM and the CPE may be communicatively coupled viaa number of possible means, including an Ethernet interface, a USB(Universal Serial Bus) interface, a wireless interface, and/or someother interface. The external network may be the Internet itself, or,alternatively a wide area network (WAN). For example, the CMcommunication system 200 is operable to allow Internet protocol (IP)traffic to achieve transparent bi-directional transfer between aCMTS-network side interface (CMTS-NSI: viewed as being between the CMTSand the Internet) and a CM to CPE interface (CMCI: viewed as beingbetween the Cable Modem (CM) and the CPE).

The Internet, and/or the WAN, is/are communicatively coupled to the CMTSvia the CMTS-NSI. The CMTS is operable to support the external networktermination, for one or both of the WAN and the Internet. The CMTSincludes a modulator and a demodulator to support transmitter andreceiver functionality to and from a CM network segment. A CMTS MediaAccess Controller (MAC) in interposed between the modulator and ademodulator of the CMTS that is operable to support CM transmissioninstruction functionality in some embodiments. In addition, the CMincludes a modulator and a demodulator to support transmitter andreceiver functionality to and from a CM network segment. A CM MediaAccess Controller (MAC) in interposed between the modulator and ademodulator of the CM that is operable to support attenuatedtransmission adaptation functionality.

A number of elements may be included within the CM network segment. Forexample, routers, splitters, couplers, relays, and amplifiers may becontained within the CM network segment without departing from the scopeand spirit of the invention. The CM network segment allows communicativecoupling between a CM user and the CMTS.

The FIG. 1 and the FIG. 2 show just two embodiments where the variousaspects of the invention may be implemented. Several other embodimentsare described as well.

FIG. 3 is a system diagram illustrating an embodiment of a satellitecommunication system that is built according to the invention. Asatellite transmitter is communicatively coupled to a satellite dishthat is operable to communicate with a satellite. The satellitetransmitter may also be communicatively coupled to a wired network. Thiswired network may include any number of networks including the Internet,proprietary networks, and/or other wired networks. The satellitetransmitter employs the satellite dish to communicate to the satellitevia a wireless communication channel. The satellite is able tocommunicate with one or more satellite receivers, shown as satellitereceivers (each having a satellite dish). Each of the satellitereceivers may also be communicatively coupled to a display.

Here, the communication to and from the satellite may cooperatively beviewed as being a wireless communication channel, or each of thecommunication to and from the satellite may be viewed as being twodistinct wireless communication channels.

For example, the wireless communication “channel” may be viewed as notincluding multiple wireless hops in one embodiment. In otherembodiments, the satellite receives a signal received from the satellitetransmitter (via its satellite dish), amplifies it, and relays it tosatellite receiver (via its satellite dish); the satellite receiver mayalso be implemented using terrestrial receivers such as satellitereceivers, satellite based telephones, and/or satellite based Internetreceivers, among other receiver types. In the case where the satellitereceives a signal received from the satellite transmitter (via itssatellite dish), amplifies it, and relays it, the satellite may beviewed as being a “transponder.” In addition, other satellites may existthat perform both receiver and transmitter operations in cooperationwith the satellite. In this case, each leg of an up-down transmissionvia the wireless communication channel would be considered separately.

In whichever embodiment, the satellite communicates with the satellitereceiver. The satellite receiver may be viewed as being a mobile unit incertain embodiments (employing a local antenna); alternatively, thesatellite receiver may be viewed as being a satellite earth station thatmay be communicatively coupled to a wired network in a similar manner inwhich the satellite transmitter may also be communicatively coupled to awired network.

The satellite transmitter is operable to support attenuated transmissionadaptation functionality according to the invention. Each of thesatellite receivers is operable, in certain embodiments, to supportsatellite transmission instruction functionality such that a satellitereceiver is capable to instruct the satellite transmitter regarding howthe satellite transmitter is to change its transmission operatingparameters.

The FIG. 3 shows yet another of the many embodiments where attenuatedtransmission adaptation functionality is supported at a transmitter endof a communication system and transmission instruction functionality maysometimes be supported at the receiver end of the communication channel.

FIG. 4 is a system diagram illustrating an embodiment of a HighDefinition Television (HDTV) communication system that is builtaccording to the invention. An HDTV transmitter is communicativelycoupled to a tower. The HDTV transmitter, using its tower, transmits asignal to a local tower dish via a wireless communication channel. Thelocal tower dish communicatively couples to an HDTV set top box receivervia a coaxial cable. The HDTV set top box receiver includes thefunctionality to receive the wireless transmitted signal that has beenreceived by the local tower dish; this may include any transformationand/or down-converting as well to accommodate any up-converting that mayhave been performed before and during transmission of the signal fromthe HDTV transmitter and its tower.

The HDTV set top box receiver is also communicatively coupled to an HDTVdisplay that is able to display the demodulated and decoded wirelesstransmitted signals received by the HDTV set top box receiver and itslocal tower dish. The HDTV transmitter (via its tower) transmits asignal directly to the local tower dish via the wireless communicationchannel in this embodiment. In alternative embodiments, the HDTVtransmitter may first receive a signal from a satellite, using asatellite earth station that is communicatively coupled to the HDTVtransmitter, and then transmit this received signal to the to the localtower dish via the wireless communication channel. In this situation,the HDTV transmitter operates as a relaying element to transfer a signaloriginally provided by the satellite that is destined for the HDTV settop box receiver. For example, another satellite earth station may firsttransmit a signal to the satellite from another location, and thesatellite may relay this signal to the satellite earth station that iscommunicatively coupled to the HDTV transmitter. The HDTV transmitterperforms receiver functionality and then transmits its received signalto the local tower dish.

In even other embodiments, the HDTV transmitter employs its satelliteearth station to communicate to the satellite via a wirelesscommunication channel. The satellite is able to communicate with a localsatellite dish; the local satellite dish communicatively couples to theHDTV set top box receiver via a coaxial cable. This path of transmissionshows yet another communication path where the HDTV set top box receivermay communicate with the HDTV transmitter.

In whichever embodiment and whichever signal path the HDTV transmitteremploys to communicate with the HDTV set top box receiver, the HDTV settop box receiver is operable to receive communication transmissions fromthe HDTV transmitter.

The HDTV transmitter is operable to support attenuated transmissionadaptation functionality according to the invention. The HDTV set topbox receiver is operable, in certain embodiments, to support HDTVtransmitter transmission instruction functionality such that the HDTVset top box receiver is capable to instruct the HDTV transmitterregarding how the HDTV transmitter is to change its transmissionoperating parameters.

The FIG. 4 shows yet another of the many embodiments where attenuatedtransmission adaptation functionality is supported at a transmitter endof a communication system and transmission instruction functionality maysometimes be supported at the receiver end of the communication channel.

FIG. 5A and FIG. 5B are system diagrams illustrating embodiment ofuni-directional cellular communication systems that are built accordingto the invention.

Referring to the FIG. 5A, a mobile transmitter includes a local antennacommunicatively coupled thereto. The mobile transmitter may be anynumber of types of transmitters including a one way cellular telephone,a wireless pager unit, a mobile computer having transmit functionality,or any other type of mobile transmitter. The mobile transmittertransmits a signal, using its local antenna, to a cellular tower via awireless communication channel. The cellular tower is communicativelycoupled to a base station receiver; the receiving tower is operable toreceive data transmission from the local antenna of the mobiletransmitter that has been communicated via the wireless communicationchannel. The cellular tower communicatively couples the received signalto the base station receiver.

The mobile transmitter is operable to support attenuated transmissionadaptation functionality according to the invention. The base stationreceiver is operable, in certain embodiments, to support transmissioninstruction functionality such that the base station receiver is capableto instruct the mobile transmitter regarding how the mobile transmitteris to change its transmission operating parameters. The FIG. 5A shows auni-directional cellular communication system where the communicationgoes from the mobile transmitter to the base station receiver via thewireless communication channel.

Referring to the FIG. 5B, a base station transmitter includes a cellulartower communicatively coupled thereto. The base station transmitter,using its cellular tower, transmits a signal to a mobile receiver via acommunication channel. The mobile receiver may be any number of types ofreceivers including a one-way cellular telephone, a wireless pager unit,a mobile computer having receiver functionality, or any other type ofmobile receiver. The mobile receiver is communicatively coupled to alocal antenna; the local antenna is operable to receive datatransmission from the cellular tower of the base station transmitterthat has been communicated via the wireless communication channel. Thelocal antenna communicatively couples the received signal to the mobilereceiver.

The base station transmitter is operable to support attenuatedtransmission adaptation functionality according to the invention. Themobile receiver is operable, in certain embodiments, to supporttransmission instruction functionality such that the mobile receiver iscapable to instruct the base station transmitter regarding how the basestation transmitter is to change its transmission operating parameters.The FIG. 5B shows a uni-directional cellular communication system wherethe communication goes from the base station transmitter to the mobilereceiver via the wireless communication channel.

The FIG. 5C shows a bi-directional cellular communication system wherethe communication can go to and from the base station transceiver and toand from the mobile transceiver via the wireless communication channel.

Referring to the FIG. 5C, a base station transceiver includes a cellulartower communicatively coupled thereto. The base station transceiver,using its cellular tower, transmits a signal to a mobile transceiver viaa communication channel. The reverse communication operation may also beperformed. The mobile transceiver is able to transmit a signal to thebase station transceiver as well. The mobile transceiver may be anynumber of types of transceiver including a cellular telephone, awireless pager unit, a mobile computer having transceiver functionality,or any other type of mobile transceiver. The mobile transceiver iscommunicatively coupled to a local antenna; the local antenna isoperable to receive data transmission from the cellular tower of thebase station transceiver that has been communicated via the wirelesscommunication channel. The local antenna communicatively couples thereceived signal to the mobile transceiver.

The base station transceiver is operable to support attenuatedtransmission adaptation functionality according to the invention as wellas transmission instruction functionality, in certain embodiments, suchthat the base station transceiver is capable to instruct the mobiletransceiver regarding how the mobile transceiver is to change itstransmission operating parameters.

Similarly, the mobile transceiver is operable, in certain embodiments,to support transmission instruction functionality such that the mobiletransceiver is capable to instruct the base station transceiverregarding how the base station transceiver is to change its transmissionoperating parameters.

The FIG. 5A, the FIG. 5B, and the FIG. 5C show yet more embodimentswhere attenuated transmission adaptation functionality is supported atthe transmitter capable end (or ends) of a communication system andtransmission instruction functionality may sometimes be supported at thereceiver capable end (or ends) of the communication channel.

FIG. 6A is a system diagram illustrating embodiment of a uni-directionalmicrowave communication system that is built according to the invention.A microwave transmitter is communicatively coupled to a microwave tower.The microwave transmitter, using its microwave tower, transmits a signalto a microwave tower via a wireless communication channel. A microwavereceiver is communicatively coupled to the microwave tower. Themicrowave tower is able to receive transmissions from the microwavetower that have been communicated via the wireless communicationchannel.

The microwave transmitter is operable to support attenuated transmissionadaptation functionality according to the invention. The microwavereceiver is operable, in certain embodiments, to support transmissioninstruction functionality such that the microwave receiver is capable toinstruct the microwave transmitter regarding how the microwavetransmitter is to change its transmission operating parameters.

The FIG. 6A shows yet another of the many embodiments where attenuatedtransmission adaptation functionality is supported at a transmitter endof a communication system and transmission instruction functionality maysometimes be supported at the receiver end of the communication channel.

FIG. 6B is a system diagram illustrating embodiment of a bi-directionalmicrowave communication system that is built according to the invention.Within the FIG. 6B, a first microwave transceiver is communicativelycoupled to a first microwave tower. The first microwave transceiver,using the first microwave tower (the first microwave transceiver'smicrowave tower), transmits a signal to a second microwave tower of asecond microwave transceiver via a wireless communication channel. Thesecond microwave transceiver is communicatively coupled to the secondmicrowave tower (the second microwave transceiver's microwave tower).The second microwave tower is able to receive transmissions from thefirst microwave tower that have been communicated via the wirelesscommunication channel. The reverse communication operation may also beperformed using the first and second microwave transceivers.

Each of the microwave transceivers is operable to support attenuatedtransmission adaptation functionality according to the invention. Inaddition, each of the microwave transceivers is operable, in certainembodiments, to support transmission instruction functionality such thatone of the microwave transceivers is capable to instruct the othermicrowave transceiver regarding how that microwave transceiver is tochange its transmission operating parameters to the other microwavetransceiver.

The FIG. 6A and the FIG. 6B show yet more embodiments where attenuatedtransmission adaptation functionality is supported at the transmittercapable end (or ends) of a communication system and transmissioninstruction functionality may sometimes be supported at the receivercapable end (or ends) of the communication channel.

FIG. 7A is a system diagram illustrating embodiment of a uni-directionalpoint-to-point radio communication system that is built according to theinvention. A mobile unit transmitter includes a local antennacommunicatively coupled thereto. The mobile unit transmitter, using itslocal antenna, transmits a signal to a local antenna of a mobile unitreceiver via a wireless communication channel.

The mobile unit transmitter is operable to support attenuatedtransmission adaptation functionality according to the invention. Inaddition, the mobile unit receiver is operable, in certain embodiments,such that the mobile unit receiver is capable to instruct the mobileunit transmitter regarding how the mobile unit transmitter is to changeits transmission operating parameters.

FIG. 7B is a system diagram illustrating embodiment of a bi-directionalpoint-to-point radio communication system that is built according to theinvention. Within the FIG. 7B, a first mobile unit transceiver iscommunicatively coupled to a first local antenna. The first mobile unittransceiver, using the first local antenna (the first mobile unittransceiver's local antenna), transmits a signal to a second localantenna of a second mobile unit transceiver via a wireless communicationchannel. The second mobile unit transceiver is communicatively coupledto the second local antenna (the second mobile unit transceiver's localantenna). The second local antenna is able to receive transmissions fromthe first local antenna that have been communicated via the wirelesscommunication channel. The reverse communication operation may also beperformed using the first and second mobile unit transceivers.

Each of the mobile unit transceivers is operable to support attenuatedtransmission adaptation functionality according to the invention. Inaddition, each of the mobile unit transceivers is operable, in certainembodiments, to support transmission instruction functionality such thatone of the mobile unit transceivers is capable to instruct the othermobile unit transceiver regarding how that microwave transceiver is tochange its transmission operating parameters to the other microwavetransceiver.

The FIG. 7A and the FIG. 7B show yet more embodiments where attenuatedtransmission adaptation functionality is supported at the transmittercapable end (or ends) of a communication system and transmissioninstruction functionality may sometimes be supported at the receivercapable end (or ends) of the communication channel.

FIG. 8A is a system diagram illustrating an embodiment of auni-directional communication system that is built according to theinvention. A transmitter communicates to a receiver via auni-directional communication channel. The uni-directional communicationchannel may be a wireline (or wired) communication channel or a wirelesscommunication channel without departing from the scope and spirit of theinvention. The wired media by which the uni-directional communicationchannel may be implemented are varied, including coaxial cable,fiber-optic cabling, and copper cabling, among other types of “wiring.”Similarly, the wireless manners in which the uni-directionalcommunication channel may be implemented are varied, including satellitecommunication, cellular communication, microwave communication, andradio communication, among other types of wireless communication.

The transmitter is operable to support attenuated transmissionadaptation functionality according to the invention. In addition, thereceiver is operable, in certain embodiments, such that the receiver iscapable to instruct the transmitter regarding how the transmitter is tochange its transmission operating parameters.

FIG. 8B is a system diagram illustrating an embodiment of abi-directional communication system that is built according to theinvention. Within the FIG. 8B, a first transceiver is communicativelycoupled to a second transceiver via a bi-directional communicationchannel. The bi-directional communication channel may be a wireline (orwired) communication channel or a wireless communication channel withoutdeparting from the scope and spirit of the invention. The wired media bywhich the bi-directional communication channel may be implemented arevaried, including coaxial cable, fiber-optic cabling, and coppercabling, among other types of “wiring.” Similarly, the wireless mannersin which the bi-directional communication channel may be implemented arevaried, including satellite communication, cellular communication,microwave communication, and radio communication, among other types ofwireless communication.

Each of the transceivers is operable to support attenuated transmissionadaptation functionality according to the invention. In addition, eachof the transceivers is operable, in certain embodiments, to supporttransmission instruction functionality such that one of the transceiversis capable to instruct the other transceiver regarding how thattransceiver is to change its transmission operating parameters to theother transceiver.

FIG. 8C is a system diagram illustrating an embodiment of a one to manycommunication system that is built according to the invention. Atransmitter is able to communicate, via broadcast in certainembodiments, with a number of receivers, shown as receivers 1, 2, . . ., n via a uni-directional communication channel. The uni-directionalcommunication channel may be a wireline (or wired) communication channelor a wireless communication channel without departing from the scope andspirit of the invention. The wired media by which the bi-directionalcommunication channel may be implemented are varied, including coaxialcable, fiber-optic cabling, and copper cabling, among other types of“wiring.” Similarly, the wireless manners in which the bi-directionalcommunication channel may be implemented are varied, including satellitecommunication, cellular communication, microwave communication, andradio communication, among other types of wireless communication.

A distribution point is employed within the one to many communicationsystem to provide the appropriate communication to the receivers 1, 2, .. . , and n. In certain embodiments, the receivers 1, 2, . . . , and neach receive the same communication and individually discern whichportion of the total communication is intended for themselves.

The transmitter is operable to support attenuated transmissionadaptation functionality according to the invention. In addition, eachof the receivers is operable, in certain embodiments, to supporttransmission instruction functionality such any one or more of thereceivers may be capable to instruct the transmitter regarding how thattransmitter is to change its transmission operating parameters forfuture transmissions to the receivers 1, 2, . . . and n.

The FIG. 8A, the FIG. 8B, and the FIG. 8C show yet more embodimentswhere attenuated transmission adaptation functionality is supported atthe transmitter capable end (or ends) of a communication system andtransmission instruction functionality may sometimes be supported at thereceiver capable end (or ends) of the communication channel.

FIG. 9 is a system diagram illustrating an embodiment of a Cable ModemTermination System (CMTS) system that is built according to theinvention. The CMTS system includes a CMTS Medium Access Controller(MAC) that operates with a number of other devices to performcommunication from one or more CMs to a WAN. The CMTS MAC is operable tosupport transmission instruction functionality such that is may directany one or more Cable Modems (CMs) that are located downstream from theCMTS system.

The CMTS MAC may be viewed as providing the hardware support forMAC-layer per-packet functions including fragmentation, concatenation,and payload header suppression that all are able to offload theprocessing required by a system central processing unit (CPU). This willprovide for higher overall system performance. In addition, the CMTS MACis able to provide support for carrier class redundancy via timestampsynchronization across a number of receivers, shown as a receiver 1,receiver 2, . . . , and a receiver n. Each receiver is operable toreceive upstream analog inputs. In certain embodiments, each of thereceivers 1, 2, . . . , and n is a dual universal advanced TDMA/CDMA(Time Division Multiple Access/Code Division Multiple Access) PHY-layerburst receiver. That is to say, each of the receivers 1, 2, . . . , andn includes at least one TDMA receive channel and at least one CDMAreceive channel; in this case, each of the receivers 1, 2, . . . , and nmay be viewed as being multi-channel receivers. In other embodiments,the receivers 1, 2, . . . , and n includes only CDMA receive channels.

In addition, the CMTS MAC may be operated remotely with arouting/classification engine that is located externally to the CMTS MACfor distributed CMTS applications including mini fiber nodeapplications. Moreover, a Standard Programming Interface (SPI) masterport may be employed to control the interface to the receivers 1, 2, . .. , and n as well as to a downstream modulator.

The CMTS MAC may be viewed as being a highly integrated CMTS MACintegrated circuit (IC) for use within the various DOCSIS and advancedTDMA/CDMA physical layer (PHY-layer) CMTS products. The CMTS MAC employssophisticated hardware engines for upstream and downstream paths. Theupstream processor design is segmented and uses two banks of SynchronousDynamic Random Access Memory (SDRAM) to minimize latency on internalbuses. The two banks of SDRAM used by the upstream processor are shownas upstream SDRAM (operable to support keys and reassembly) and SDRAM(operable to support Packaging, Handling, and Storage (PHS) and outputqueues). The upstream processor performs Data Encryption Standard (DES)decryption, fragment reassembly, de-concatenation, payload packetexpansion, packet acceleration, upstream Management Information Base(MIB) statistic gathering, and priority queuing for the resultantpackets. Each output queue can be independently configured to outputpackets to either a Personal Computer Interface (PCI) or a Gigabit MediaIndependent Interface (GMII). DOCSIS MAC management messages andbandwidth requests are extracted and queued separately from data packetsso that they are readily available to the system controller.

The downstream processor accepts packets from priority queues andperforms payload header suppression, DOCSIS header creation, DESencryption, Cyclic Redundancy Check (CRC) and Header Check Sequence (ofthe DOCSIS specification), Moving Pictures Experts Group (MPEG)encapsulation and multiplexing, and timestamp generation on the in-banddata. The CMTS MAC includes an out-of-band generator and CDMA PHY-layer(and/or TDMA PHY-layer) interface so that it may communicate with a CMdevice's out-of-band receiver for control of power management functions.The downstream processor will also use SDRAM (operable to support PHSand output queues). The CMTS MAC may be configured and managedexternally via a PCI interface and a PCI bus.

The FIG. 9 shows yet another embodiment where transmission instructionfunctionality may sometimes be supported at the receiver capable end ofthe communication channel, specifically at the CMTS end of a cable modemcommunication system.

FIG. 10A is a diagram illustrating logical channel partitioning of aportion of spectrum that is performed according to the invention. Theattenuated transmission adaptation functionality and methods describedherein may also be implemented using logical channel partitioning of anumber of available dimensions of a communication channel. The availabledimensions may be time, as in a communication system employing TimeDivision Multiple Access (TDMA), or alternatively, codes, as in acommunication system employing Code Division Multiple Access (CDMA), ora combination thereof.

For example, a communication channel (e.g., a radio frequency spectrumband, or portion thereof) may be partitioned into a number of logicalchannels. A given logical channel is active for a certain number offrames (e.g., for a predetermined time duration), then another logicalchannel is active, and so on, one at a time. This is typically referredto as TDMA with respect to the means of sharing the spectrum amonglogical channels.

However, the concept of logical channel partitioning may be extendedsuch logical channels may be implemented as multi-dimensional logicalchannels. For example, a logical channel may be implemented to exist in2 dimensions, such as time and code. This is a 2 dimensional logicalchannel. In this 2 dimensional approach, the given 2 dimensional logicalchannel would be active during a given set of contiguous frames (orportions of information), and in a certain set of codes. This wouldpermit several logical channels to be active simultaneously, while beingseparated in code space. Similarly, the multi-dimensional logicalchannel concept may be extended to cover higher orders ofdimensionality. For example, a logical channel may be implemented toexist in 3 dimensions, such as time, code, and frequency. Clearly, thisdimensionality may be extended to an n-dimensional logical channelwithout departing from the scope and spirit of the invention.

While the FIG. 10A shows a communication system employinguni-directional communication between a transmitting device and areceiving device, the invention envisions performing logical channelpartitioning within both directions of a bi-directional communicationsystem as well.

FIG. 10B is a diagram illustrating an embodiment of logical channelpartitioning of Synchronous Code Division Multiple Access (S-CDMA) codesin a Data Over Cable Service Interface Specification (DOCSIS) systemthat is performed according to the invention. The FIG. 10B shows how thelogical channel partitioning may be employed based on the 128 codes thatare currently available according to DOCSIS. For example, a logicalchannel 1 may be comprised of codes 1 through 64 of DOCSIS, and alogical channel 2 may be comprised of codes 65 through 128 of DOCSIS. Athird logical channel, logical channel 3, may be comprised of all 128codes or of logical channels 1 and 2.

The selection of which 64 DOCSIS codes will be used to comprise thelogical channel 1 and which 64 DOCSIS codes will be used to comprise thelogical channel 2 may be performed using a CMTS MAC.

In some embodiments, when a CM isn't in a highly attenuated path (thatis, upstream path to the CMTS), then that CM would be able to receivegrants on either the full 128 code logical channel (logical channel 3)or either of the 64 code logical channels (logical channels 1 or 2). The128 code logical channel (logical channel 3) is again equivalent to thecombined two logical channels of 64 codes (logical channels 1 or 2).

It is also noted that the grouping of codes into logical channels neednot be performed such that the codes are adjacent to one another. Forexample, either of the 64 code logical channels (logical channels 1 or2) may select the 64 channels from among all of the 128 available codes;for example, logical channel 1 may include codes, 1, 3, 4, 6, 10, and soon, including a total number of codes being 64.

FIG. 11 is a diagram illustrating an alternative embodiment of logicalchannel partitioning of S-CDMA codes in a DOCSIS system that isperformed according to the invention. Again, the FIG. 11 shows anembodiment of how channel partitioning may be performed using the 128codes of a DOCSIS communication system. If a CM is in an attenuatedchannel situation (between the CM and the CMTS) where it must onlytransmit on, for example, Npc=8 codes, then the available channel may bedivide into a set of logical channels such that at least one (or acombination thereof) of the logical channels will permit transmissionusing 8 codes.

As an example, the 128 DOCSIS codes may be partitioned into logicalchannels as follows: logical channel 1 with Nc1=8 codes, logical channel2 with Nc2=32 codes, and logical channel 3 with Nc3=88 codes. It isnoted that Nc1+Nc2+Nc3=Nac=128 codes, so that all of the active codes(Nac) may be accounted by all of the logical channels.

In certain embodiments, a given CM may be assigned to one of theselogical channels (e.g., logical channel 1), and transmit the reducednumber of codes (e.g., 8 codes). Accordingly, with increased power percode (e.g., 8 times more power per code) may also be employed toovercome the attenuated channel. This power adaptation functionality isdescribed in more detail below.

As an extension of the concept, a CM may be assigned to more than one ofthe logical channels that comprise codes. For example, a CM may beassigned to logical channels 2 and 3. In this case it would be assignedNc2+Nc3=120 codes. This provides even more flexibility in assigningnumbers of codes per CM. In addition, for a CM whose upstream path tothe CMTS does not experience much attenuation, then a 4^(th) logicalchannel that includes all of these 3 logical channels may be usedthereby making all 128 codes available to that CM.

It is noted that the invention is adaptable to communication systemsthat employ modulation techniques having orthogonal waveforms. Theinvention may also be extended to other communication systems that othercommunication systems that employ a signal space having orthogonalsignals contained therein.

For example, in addition to orthogonal waveforms and signaling schemessuch as code division multiple access (CDMA) signaling dimensions,synchronous code division multiple access (S-CDMA) signaling dimensions,time division multiple access (TDMA) signaling dimensions, etc., thereare also other orthogonal waveforms and signaling schemes such asorthogonal frequency division multiplexing (OFDM) signaling dimensions,discrete multi-tone (DMT) signaling dimensions, etc., such as describedin U.S. utility patent application Ser. No. 10/142,189, now U.S. Pat.No. 7,110,434, which is incorporated herein by reference above, that mayalso be adapted to employ various of the principles described herein.

One particular example of a communication system employing orthogonalwaveforms includes a communication system employing Synchronous CodeDivision Multiple Access (S-CDMA) codes. The orthogonal waveforms havethe property that multiple waveforms (e.g., codes in DOCSIS 2.0 S-CDMA)can be transmitted simultaneously by a given transmitting device. Thetotal number of codes that may be is use anywhere on a communicationchannel are referred herein as the number of active codes (the number ofcodes in use anywhere on the channel) and they are denoted Nac.

As also mentioned above with respect to FIG. 10, it is also noted thatthe grouping of codes into logical channels need not be performed suchthat the codes are adjacent to one another.

FIG. 12 is a functional block diagram illustrating an embodiment ofpower and modulation adaptation functionality that is arranged accordingto the invention. This figure shows the power and modulation adaptationfunctionality being supported within a communication system having atransmitting device and a receiving device. However, the functionalitydescribed herein may also be implemented within transceiver type devicesthat also support both receive and transmit functionality.

The transmitting device is implemented to support attenuatedtransmission adaptation functionality. The receiving device may beimplemented to support transmission instruction functionality. Thereceiving device may be the source of instructions provides to thetransmitting device, the transmitting device may initiate operationsaccording to the attenuated transmission adaptation functionalitycontained therein, or a combination thereof may be implemented.

As shown within the power adaptation functional block, a giventransmitting device is instructed to reduce the number of codes it cantransmit to Npc, or number of permitted codes. Again, the total numberof available codes that can be used anywhere on the system is denoted asNac (total number of active codes). In general Npc<Nac. This reductionin codes to the number of permitted codes, Npc, reduces the availableburst throughput of that individual transmitting device by the factorNpc/Nac. Other transmitting devices on the network are permitted totransmit on the remaining codes; this has the benefit that the overallthroughput of the communication channel is not affected by thelimitation on this individual transmitting device.

The unused codes (those codes of Nac that are left over after thereduction has been made to Npc, the number of unused codes beingNac−Npc) may be used to perform interference cancellation according tothe invention.

In addition, the transmitting device is also instructed to increase itspermitted power per code by the factor Nac/Npc which is substantiallythe inverse of the factor by which the number of transmitting codes hasbeen reduced. This may even give the transmitting device a higher Signalto Noise Ratio (SNR) at the receiving device by the same factor Nac/Npc.When the transmitting device is using all Npc of its codes, itstransmitted power is the same as if it were if permitted to use Naccodes with the original amount of power per code. That is, the decreasein the number of codes transmitted, and the increase in power per code,will substantially cancel one another, and the maximum power transmitcapability of the transmitting device will remain unchanged. This hasthe benefit that the power limitation of the transmitting device is notexceeded, even though the receive SNR is either maintained or increased.

As shown within modulation adaptation functional block, when thetransmitting device is transmitting with this reduced number ofpermitted codes, the transmitting device may continue to use the sameupstream burst profile as before. For example, if a high ordermodulation density, such as 64 QAM (Quadrature Amplitude Modulation) wasused before the instruction to decrease the number of transmitting codeswas received, then the same high order modulation density may also beused afterwards as well. This gives a significant benefit, in that, anyother transmitting devices on the network are not required to reducetheir upstream burst profiles. It gives even another benefit that thetotal throughput and throughput efficiency on the communication channelmay remain unchanged.

FIG. 13 is a functional block diagram illustrating an embodiment ofranging and registering functionality that is arranged according to theinvention. A transmitting device is operable to support robust modeoperation to do ranging and registering using a group of maximallyrobust burst parameters and the ranging and registering may be performedacross a robust logical channel. The maximally robust burst parametersmay be achieved using a variety of means, and some possible means aredescribed below.

A highly robust and low order modulation may be employed to support therobust mode operation. Some examples of highly robust and low ordermodulation may include BPSK (Binary Phase Shift Keying) modulation, QPSK(Quadrature Phase Shift Keying) and/or QPSK TCM (QPSK Trellis CodedModulation).

In addition, the Forward Error Correction (FEC) of the communicationsystem, that is typically performed in a receiving device, may also becontrolled using parameters stored within the transmitting device. Forexample, the transmitting device may provide information to thereceiving device that it is to use the maximal setting of anyReed-Solomon error correction capability contained therein.

Moreover, even other means may be performed by which the robust modeoperation may be supported. For example, preamble estimation may bemodified by the receiving device as governed by the transmitting device.The transmitting device is able to send ranging bursts to the receivingdevice. These ranging burst sent by the transmitting device are designedto permit accurate parameter estimation at the receiving device. Forexample, the transmitting device may send an extended preamble(sometimes referred to as a long preamble), or multiple copies of thepreamble, and the receiving device may average its estimates over themultiple copies of the preamble. The extended preamble/long preamblebeing longer than a preamble typically employed within the communicationsystem.

It is noted that a key element here, to support robust mode operation,is that the ranging may take place using a lower order modulation suchas QPSK, at a relatively low SNR such as 10 dB, but the parameterestimates are of high enough quality to support eventual transmission ata higher order modulation, such as 16 QAM or 64 QAM, at a higher SNRsuch as 25 dB. This higher SNR may be achieved, as described above, byincreasing the power per code while using fewer codes. In addition, therobust mode operation may perform the parameter estimation, and thatparameter estimation may then indicate that a higher order modulationmay subsequently be employed. In so, then the transmitting device willoperate at that higher order modulation, such as 16 QAM or 64 QAM, amongother higher order modulation types.

Alternatively, power modification functionality may be employed toprovide for the robust mode operation. The transmitting device mayincrease the transmit power where possible given physical amplifierconstraints, or the transmitting device may increase the averagetransmit power via reduction in peak-to-average ratio, among other powermodification that may be performed to support the robust mode operation.

A means is utilized to communicate to the transmitting device that itneeds to enter this robust mode. Such a means may include a separatelogical channel, and/or a proprietary communications channel via thedownstream. In the context of a cable modem communication system, thiscommunication may be achieved using the CM network segment itself.

It is also noted that when a transmitting device first attempts to enterthe network, it may have to follow a logical decision process todetermine if it should go into this robust mode. That is to say, thetransmitting device may perform an initialization routine, when enteringthe network, to determine if robust mode operation is even needed atall.

FIG. 14A is a diagram illustrating example upstream burst profiles thatmay be employed according to the invention. A spectrum of upstream databurst profiles may be used. Generically speaking, a higher order profileand a lower order profile may be used. The higher order profile may beviewed as having a relatively shorter preamble, a relatively highermodulator density, relatively weak Forward Error Correction (FEC), anequalizer tap coefficient set1, a reflection coefficients set1, andother parameters as required or desired. The higher order profile may beviewed as being operable on a channel whose characteristics can supportthis higher order level of processing. A relatively accurate channelestimation and channel equalization may need to be performed toaccommodate upstream data bursting using the higher order profile.

The lower order profile may be viewed as having a relatively longerpreamble (when compared to the shorter preamble of the higher orderprofile), a relatively lower modulator density (when compared to thehigher order modulator density of the higher order profile), relativelypowerful FEC (when compared to the weaker FEC of the higher orderprofile), an equalizer tap coefficient set2, a reflection coefficientsset2, and other parameters as required or desired; the parameters of thelower order profile are much more robust than the parameters of thehigher order profile. The lower order profile may be viewed as beingoperable on a channel whose characteristics are unable to support thehigher order level of processing within the higher order profile. Arelatively accurate channel estimation and channel equalization may notbe available or may be unable to be performed to accommodate upstreamdata bursting using the higher order profile, the invention thenprovides operation using the lower order profile.

This figure shows a spectrum of available upstream data burst profilesthat may be used according to the invention to perform and continueupstream data bursting from the CMs to the CMTS. Operation at the lowerorder profile will provide sufficient protection to ensure that theupstream data burst will get through even when the channel may becorrupted. Each of the upstream data burst profiles includes amodulation density. The modulation density may be viewed as being oneparameter within an upstream data burst profile. If desired, and as willbe shown and described in various embodiments, various profiles may beemployed when performing upstream data bursting according to theinvention; or alternatively, only various modulation densities may beemployed when performing upstream data bursting according to theinvention. Clearly, other operational parameters may be used todifferentiate and continue upstream data bursting when desiring tooperate at a more (or less) robust operational state.

FIG. 14B is a diagram illustrating example modulation densities that maybe employed according to the invention. The spectrum of modulationdensities involves higher order modulation densities and lower ordermodulation densities. For example, the spectrum of modulation densitiesranges from 1024 QAM (Quadrature Amplitude Modulation), 256 QAM, 64 QAM,16 QAM, QPSK (Quadrature Phase Shift Keying), and BPSK (Binary PhaseShift Keying). Other modulation schemes could similarly be employed andarranged in an increasing/decreasing order of density without departingfrom the scope and spirit of the invention. The higher order modulationdensities may be viewed as including the 1024 QAM and 256 QAM, and thelower order modulation densities may be viewed as including the 16 QAM,QPSK, and BPSK. In some embodiments, a higher order modulation densitymay be viewed as including only 16 QAM, and a lower order modulationdensity may be viewed as including only QPSK.

The higher order modulation densities may be used within thosecommunication channels (which may be logical channel and/ormulti-dimensional logical channels) that have been adequately ranged andregistered to support that level of modulation density, and the loworder modulation densities may be used within those channels that havenot yet been adequately ranged and registered to support higher levelsof modulation density. In addition, the low order modulation densitiesmay be used to perform the actual ranging and registering of a CM onto anew channel (such as a logical channel and/or a multi-dimensionallogical channel).

FIG. 15 is an operational flow diagram illustrating an embodiment of anattenuated transmission adaptation method, employing power andmodulation adaptation, that is performed according to the invention. Itis noted that the method described herein may operate using anembodiment of the multi-dimensional logical channels described in moredetail above.

As shown in a block 1510, a given CM is instructed to reduce the numberof codes it can transmit to Npc, or number of permitted codes, from thetotal number of active codes Nac. In general Npc<Nac. This reduces theavailable burst throughput of that individual CM by the factor Npc/Nac.Any other CMs on the network will be permitted to transmit on theremaining codes; this has the benefit that the overall throughput of thechannel is not affected by the limitation on this individual CM.

If desired in certain embodiments, these now unused codes, codes of Nacthat are not included in Npc, may be employed to perform interferencecancellation as shown in a block 1515. In an alternative embodiment,these unused codes may a subset of codes within a logical channel; thelogical channel may also be implemented as a multi-dimensional logicalchannel without departing from the scope and spirit of the invention.

Continuing on with the method, as shown in a block 1520, the CM is alsoinstructed to increase its permitted power per code by the factorNac/Npc for the remaining permitted codes, Npc. This may be viewed asincreasing the power per code form a 1^(st) power per code to a 2^(nd)power per code. This gives the CM a higher SNR at the CMTS by the samefactor Nac/Npc. When the CM is using all Npc of its codes, the totaltransmitted power of the CM may be maintained the same as if it were ifpermitted to use Nac codes with the original amount of power per code.That is, the decrease in the number of codes transmitted, and theincrease in power per code, will substantially cancel one another, andthe maximum power transmitted by the CM is unchanged. This has thebenefit that the power limitation of the CM is not exceeded, even thoughthe receive SNR is increased.

Moreover, as shown in a block 1530, when transmitting with this reducednumber of permitted codes, Npc, the CM continues to use the sameupstream burst profile as before. For example, even is a higher ordermodulation density is employed beforehand, such as 64 QAM, then the samehigher order modulation density may be employed after reducing thenumber to transmitting codes from Nac to Npc. This gives a benefit thatany other CMs on the cable modem network are not required to reducetheir upstream burst profiles. It gives yet another benefit, in that,the total throughput and throughput efficiency on the communicationchannel may remain unchanged.

FIG. 16 is an operational flow diagram illustrating an embodiment of anattenuated transmission adaptation method, employing ranging andregistering adaptation, that is performed according to the invention.

A CM is given the means to range and register using the maximally robustburst parameters. Such a robust parameter set may include BPSKmodulation, or QPSK trellis coded modulation; maximal setting ofReed-Solomon error correction capability; long preamble/extendedpreamble; increased transmit power where possible given physicalamplifier constraints; increased average transmit power via reduction inpeak-to-average ratio; etc.

As shown in a block 1610, a Cable Modem Termination System (CMTS)instructs a CM that it is to register on a separate, robust logicalchannel. In this embodiment, a means may be utilized to communicate fromthe CMTS to the CM that it needs to enter this robust mode operation.Such a means may include a separate logical channel, a proprietarycommunications channel via the downstream, and/or some othercommunication means. When a CM first attempts to enter the cable modemnetwork, the CM may have to follow a logical decision process todetermine if it should go into this robust mode operation.Alternatively, as shown in a block 1615, the CM itself employs built-inintelligence that is used to initiate a search for a separate, robustlogical channel. In yet another embodiment, a combination thereof may beemployed where the CM and the CMTS operate cooperatively to search forthe separate, robust logical channel.

In whichever embodiment of the blocks 1610 or 1615 is employed, themethod continues, as shown in a block 1620, such that the CM switches tothe separate, robust logical channel.

As shown in a block 1630, ranging bursts sent by the CM are designed topermit accurate parameter estimation at the CMTS. The CMTS then performsparameter estimation of the communication channel using the rangingburst as shown in a block 1632. In addition, the CM may send an extendedpreamble, or multiple copies of the preamble, and the CMTS may averageits estimates over the multiple copies of the preamble. Specifically, asshown in a block 1635, multiple copies of a preamble are transmittedfrom the CM to the CMTS. Then, as shown in a block 1637, the CMTSperforms parameter estimation of the communication channel by averagingover the multiple copies of the preamble that have been transmitted formthe CM to the CMTS.

As shown in a block 1640, the ranging and registering of the CM iscompleted on the separate, robust logical channel. After the ranging andregistering of the CM is completed, then the CMTS instructs the CM tomove to a normal logical channel as shown in a block 1650. This normallogical channel may include a higher order upstream burst profile. Then,as shown in a block 1660, the CM operates on the normal logical channel,using higher order upstream burst parameters, but with reduced number ofpermitted codes (Npc) and increased power per code (as described abovein greater detail).

Again, it is noted that the ranging may take place using a lower ordermodulation such as QPSK, at low SNR such as 10 dB, but the parameterestimates are of high enough quality to support eventual transmission ata higher order modulation such as 64 QAM at a higher SNR such as 25 dB.This higher SNR is achieved, as described above, by increasing the powerper code while using fewer codes (again, as described above in greaterdetail).

While the methods shown within the FIGS. 15 and 16 are described in thecontext of a communication system having at least one CM and a CMTS, itis understood that the invention envisions that these methods may beperformed within any communication system having a transmitting device(shown in these examples as the CM) and a receiving device (shown inthese examples as the CMTS).

A specific example is provided to illustrate some of the more generalconcepts of the invention. This example operates on the framework of aDOCSIS 2.0 S-CDMA system, where Nac=128 active codes. For 64 QAM, a SNRof 25 dB SNR is required at the receiver (e.g., the CMTS). A given CMcan output up to 53 dBmV power in S-CDMA mode when transmitting to theCMTS, and up to 58 dBmV in TDMA mode when transmitting to the CMTS.

In this example, the assumption is made that most CMs are communicatingwith the required 25 dB SNR using 64 QAM. However, a given CM, referredto as CM 1, may have a greater attenuation due to a poorly planned cablelayout in the apartment complex. When transmitting at its maximum powerof 53 dBmV with all 128 codes, CM 1 would only produce 15 dB SNR(instead of the desired 25 dB) at the receiver (e.g., the CMTS). Henceit has a disadvantage of 10 dB that must be overcome.

The CM 1 will then attempt to enter the cable modem network, and the CM1 will find that it cannot communicate easily. It determines this factby failed ranging attempts. The cable headend (e.g., the CMTS) will theninstruct CM 1 to register on a separate robust logical channel, or theCM 1 itself has built-in intelligence that causes it to search for arobust logical channel. CM 1 then switches to the robust logicalchannel, where the upstream ranging is more robust, perhaps due to thefact that preamble lengths are longer, e.g., QPSK TCM is used, 58 dBmVor slightly more is transmitted on QPSK ranging bursts, maximumReed-Solomon (RS) Forward Error Correction (FEC) parameters are used,etc.

CM 1 then succeeds in ranging and registering on the separate, robustlogical channel. The cable headend (e.g., the CMTS) then instructs CM 1to move to the normal logical channel and begin communicating in 64 QAM,but with a reduced number of permitted codes: Npc=128/16=8 codes. Thiscauses the power per code to increase by a factor of 16. This gives CM 1an advantage of 10 log 16=12 dB, which more than overcomes thedisadvantage of 10 dB. Now CM 1 finds that its SNR at the receiver is25-27 dB, which is more than enough to communicate using a modulationdensity of 64 QAM. The burst throughput of CM 1 is of course limited bya factor of 16, but the overall throughput and throughput efficiency ofthe channel is unchanged.

FIG. 17A, FIG. 17B, FIG. 18A, and FIG. 18B are operational flow diagramsillustrating embodiments of attenuated transmission adaptation methodsthat are performed according to the invention. These various attenuatedtransmission adaptation methods may be viewed as enabling upstreamtransmission from CMs operating in an S-CDMA mode (or using a similarorthogonal spreading technique such as spread S-TDMA (Synchronous TimeDivision Multiple Access)=spread single carrier modulation) with limitedtransmit power in the presence of very large channel attenuation. Avariety of different cases are presented to show some of the manydifferent ways in which the invention may be implemented.

Referring to the FIG. 17A, this embodiment operates by reducing thenumber of simultaneously employed codes (=dimensions). One specificembodiment involves reducing the number of codes to be used from 2Ncodes to N codes; clearly, other degrees of reduction of used codes mayalso be performed without departing from the scope and spirit of theinvention. In this embodiment, the available total transmit power P isthen shared among fewer codes and hence allows for the use of thetransmit power P to be larger on a per-code basis. That is to say, eachof the used codes then employs a larger portion of the total transmitpower P.

Referring to the FIG. 17B, this embodiment operates by maintaining thesame number of employed codes (or the same number of dimensions) as isinitially employed; this involves no reduction in the number of usedcodes. For example, all 2N of the codes may be employed in one specificembodiment. Then, the method involves modulating pairs of codes with thesame modulation symbol. This may be viewed as performing repetitioncoding which may also be viewed as a reduction of the modulated signaldimensions. In the receiver, the output signals of the correspondingdespreaders are coherently added together. The SNR (Signal to NoiseRatio) of this attenuated transmission adaptation method may beimplemented to provide for precisely the same SNR as that provided bythe attenuated transmission adaptation method described with respect tothe FIG. 17A.

Referring to the FIG. 18A, this embodiment also operates by maintainingthe same number of employed codes (or the same number of dimensions) asis initially employed; this involves no reduction in the number of usedcodes. For example, all 2N of the codes may be employed in one specificembodiment.

However, in this embodiment, the coding is performed using a reducedcode rate. In one particular embodiment, this code rate reductioninvolves using 2N codes and employing a code rate that is ½ whencompared to the code rate to the attenuated transmission adaptationmethods described with respect to the FIG. 17A and the FIG. 17B. In asimplest case implementation, this embodiment takes the form of uncodedmodulation with ½ the number of information bits per symbol. Theperformance of this attenuated transmission adaptation method embodimentwill generally be better than the attenuated transmission adaptationmethod described with respect to the FIG. 17B.

Referring to the FIG. 18B, this embodiment also operates by maintainingthe same number of employed codes (or the same number of dimensions) asis initially employed; this involves no reduction in the number of usedcodes. For example, all 2N of the codes may be employed in one specificembodiment.

Again, the coding is performed using a reduced code rate. In oneparticular embodiment, this code rate reduction involves using 2N codesand employing a code rate that is ½ when compared to the code rate tothe attenuated transmission adaptation methods described with respect tothe FIG. 17A and the FIG. 17B. However, in this particular embodiment,which may be provide for the best performance according to theinvention, is employed to employ all of the 2N codes and also to employa true code rate R=½ (rate compared to that of the attenuatedtransmission adaptation methods described with respect to the FIG. 17Aand the FIG. 17B) sequence coding to pick up any additional coding gainover the attenuated transmission adaptation method described withrespect to the FIG. 18A. For example, a true ½ code rate sequence codingmay be employed to pick up additional coding gain when compared toperforming uncoded modulation as described with respect to the FIG. 18A.

In general, the various embodiments described with respect to the FIG.17A, FIG. 17B, FIG. 18A, and FIG. 18B may be summarized as follows:unless a reduction of dimensions permits to evade stronger interferencein some dimensions than in others, using all available signal dimensionswill present an optimum implementation solution according to theinvention.

Moreover, the invention relies on and extends the concept of reducingthe number of dimensions that are transmitted in order to gain anadvantage over various types of noise. This reduction in transmitteddimensions, coupled with intelligent processing at the receiver,provides an extremely large processing gain. The various embodimentsdescribed herein extend this concept to white noise, or equivalently, toincreased plant attenuation. From certain perspectives, white noise canbe thought of as a limiting case of colored noise, where the color iswhite. In the case of white noise, the processing gain may not be asgreat as for colored noise. However, the advantage (which may berealized as a 3 dB for a reduction in the number of used codes from 128down to 64 codes, and which may be realized as up to an 18 dB gain for areduction down to 2 codes, at the expense of throughput) is still worthobtaining in some communication system applications. This may be viewedas being particular useful when constraints exist on the modulationorder; this may be viewed as arising in an application where there is avery limited number of burst profiles that are available for use. Inaddition, the idea of increasing the transmitted power on the activedimensions, to take advantage of the lack of power transmitted on theinactive dimensions may be viewed in this invention as being applied tocombat the deleterious effects introduced by white noise within acommunication system.

Various aspects of the invention can be found in a communication systemthat supports attenuated transmission adaptation. The communicationsystem comprises a transmitting device communicatively coupled to areceiving device via a communication channel. The transmitting device isoperable to transmit information to the receiving device using aplurality of active codes. Each active code is transmitted using a firstpower per code. The receiving device, communicatively coupled to thetransmitting device via a communication channel, is operable to receivetransmitted information from the transmitting device. The receivingdevice instructs the transmitting device to transmit information using aplurality of permitted codes, and the receiving device also instructsthe transmitting device to transmit each permitted code using a secondpower per code. The communication channel comprises a spectrum portionthat is partitioned into a plurality of logical channels.

In certain embodiments of the invention, the transmitting device is acable modem (CM), and the receiving device is a Cable Modem TerminationSystem (CMTS). However, it is understood that a variety of differentdevices may be employed in various types of communication systemswithout departing from the scope and spirit of the invention. Forexample, the transmitting device may be any one of a satellitetransmitter, a High Definition Television (HDTV) transmitter, a mobiletransmitter, a base station transmitter, a mobile transceiver, amicrowave transmitter, or a microwave transceiver among othertransmitting device types. Analogously, the receiving device may be anyone of a satellite receiver, a High Definition Television (HDTV) set topbox receiver, a mobile receiver, a base station receiver, a mobiletransceiver, a microwave receiver, or a microwave transceiver, amongother receiving device types. In addition, the type of communicationsystem in which the invention may be employed is also varied; thecommunication system may be any one of a cable modem communicationsystem, a satellite communication system, a High Definition Television(HDTV) communication system, a cellular communication system, amicrowave communication system, a point-to-point radio communicationsystem, a uni-directional communication system, a bi-directionalcommunication system, or a one to many communication system.

The logical channels may be composed of a number of Synchronous CodeDivision Multiple Access (S-CDMA) channels in one embodiment. Moreover,the logical channels may be implemented using a plurality ofmulti-dimensional logical channels. For example, the plurality ofmulti-dimensional logical channels may be a 2 dimensional logicalchannel having a time dimension and a code dimension, or a 3 dimensionallogical channel having a time dimension, a code dimension, and afrequency dimension. The transmitting device is able to simultaneouslytransmit the information to the receiving device using two or more ofthe multi-dimensional logical channels. The plurality of active codesincludes unused codes and permitted codes. The receiving device isoperable to perform interference cancellation using the unused codes. Aratio of the first power per code over the second power per code issubstantially an inverse of a ratio of the number of active codes over anumber of permitted codes.

The transmitting device performs ranging and registering of thecommunication channel that communicatively couples the transmittingdevice and the receiving device using a plurality of maximally robustburst parameters. The transmitting device sends a ranging burst to thereceiving device via a robust logical channel; the robust logicalchannel is one of the logical channels. The maximally robust burstparameters include a highly robust and low order modulation. Themaximally robust burst parameters may include either an extendedpreamble or a plurality of copies of a preamble. The receiving device isoperable to perform parameter estimation of the communication channelusing the plurality of copies of the preamble, and the receiving devicegenerates an average parameter estimation by averaging over theplurality of copies of the preamble.

When the ranging and registering of the communication channel iscompleted, the receiving device instructs the transmitting device tomove to a multi-dimensional logical channel, and the transmitting devicesubsequently operates using the multi-dimensional logical channel whileemploying a plurality of parameters having a higher order than theplurality of maximally robust burst parameters.

The ranging and registering of the communication channel may beperformed when the receiving device instructs the transmitting device todo so, or transmitting device itself may initiate the ranging andregistering of the communication channel. The transmitting device uses amodulation when transmitting information using the plurality of activecodes. Even after the transmitting device reduces the number of codesemployed to transmit information, to the plurality of permitted codes,the ranging and registering of the communication channel may employ thatsame modulation. In addition, the communication system may operate atthe same throughput and efficiency after reducing the number of codes asit did beforehand, thereby maintaining the same throughput andefficiency of the communication system. In some instance, the Signal toNoise Ratio (SNR) that is achieved after reducing the number of codesemployed to the plurality of permitted codes is even greater than theSNR that is achieved beforehand.

Other aspects of the invention can be found in an attenuatedtransmission adaptation method. The method involves instructing a CableModem (CM), using a Cable Modem Termination System (CMTS), to reduce anumber of transmit codes from a plurality of active codes to a pluralityof permitted codes, the reduction in the number of transmit codes beinga reduction factor. The method also involves instructing the CM toincrease a transmitted power per code for each permitted code of theplurality of permitted codes by approximately an inverse of thereduction factor. The CM and the CMTS are communicatively coupled via acommunication channel, and the communication channel comprises aspectrum portion that is partitioned into a plurality of logicalchannels.

In certain embodiments, the logical channels are made up of a pluralityof multi-dimensional logical channels. The multi-dimensional logicalchannels may be 2, 3, or n-dimensional logical channels. For example,one type of a 2 dimensional logical channel includes a time dimensionand a code dimension, and one type of a 3 dimensional logical channelincludes a time dimension, a code dimension, and a frequency dimension.The CM is able to simultaneously transmit the information to the CMTSusing two or more multi-dimensional logical channels. The method mayalso involve performing ranging and registering of the communicationchannel that communicatively couples the CM and the CMTS using aplurality of maximally robust burst parameters and using a robustlogical channel. The maximally robust burst parameters may include ahighly robust and low order modulation. In addition, the maximallyrobust burst parameters may include one or more of an extended preambleand a number of copies of a preamble. The method may also involveperforming parameter estimation of the communication channel, at theCMTS, by averaging over the copies of the preamble.

The method may also involve instructing the CM, using the CMTS, to moveto a multi-dimensional logical channel when the ranging and registeringof the communication channel is completed. The method may involvesubsequently operating the CM using the multi-dimensional logicalchannel while employing parameters having a higher order than themaximally robust burst parameters. The CMTS may instruct the CM toperform the ranging and registering of the communication channel.Alternatively, the CM may itself initiate the ranging and registering ofthe communication channel.

The method also allows transmitting information across the communicationchannel, from the CM to the CMTS, at a modulation when using either theplurality of active codes or the plurality of permitted codes. Inaddition, the SNR that is provided after switching to the plurality orpermitted codes from the plurality of active codes may even be improved.Moreover, the throughput and efficiency may be maintained afterswitching to the plurality of permitted codes from the plurality ofactive codes.

While the method has been described in the context of a cable modemcommunication system, it is noted that a variety of other communicationsystems, having a transmitting device and a receiving device, may alsoperform the method described herein. Some examples of such communicationsystems include any one of a satellite communication system, a HighDefinition Television (HDTV) communication system, a cellularcommunication system, a microwave communication system, a point-to-pointradio communication system, a uni-directional communication system, abi-directional communication system, and a one to many communicationsystem.

In view of the above detailed description of the invention andassociated drawings, other modifications and variations will now becomeapparent. It should also be apparent that such other modifications andvariations may be effected without departing from the spirit and scopeof the invention.

1. An apparatus, comprising: a receiver module that is operative toreceive information transmitted from at least one additional apparatususing a plurality of orthogonal signaling dimensions via a communicationchannel; and a transmission instruction module that is operative togenerate a control signal, based upon the received information, that iseffective to instruct the at least one additional apparatus to modify atleast one of: a number of orthogonal signaling dimensions within theplurality of orthogonal signaling dimensions employed for a subsequenttransmission there from; and a power per orthogonal signaling dimensionfor at least one of the plurality of orthogonal signaling dimensions forthe subsequent transmission there from.
 2. The apparatus of claim 1,wherein: a modification of the number of orthogonal signaling dimensionswithin the plurality of orthogonal signaling dimensions is a reductionin the number of orthogonal signaling dimensions within the plurality oforthogonal signaling dimensions to a plurality of permitted orthogonalsignaling dimensions.
 3. The apparatus of claim 1, wherein: amodification of the power per orthogonal signaling dimension for the atleast one of the plurality of orthogonal signaling dimensions is anincrease of the power per orthogonal signaling dimension.
 4. Theapparatus of claim 3, wherein: a first power per orthogonal signalingdimension corresponding to a first of the plurality of orthogonalsignaling dimensions is increased by a first amount; and a second powerper orthogonal signaling dimension corresponding to a second of theplurality of orthogonal signaling dimensions is increased by a secondamount.
 5. The apparatus of claim 1, wherein: the plurality oforthogonal signaling dimensions is a plurality of code division multipleaccess (CDMA) signaling dimensions, a plurality of synchronous codedivision multiple access (S-CDMA) signaling dimensions, a plurality oftime division multiple access (TDMA) signaling dimensions, a pluralityof orthogonal frequency division multiplexing (OFDM) signalingdimensions, or a plurality of discrete multi-tone (DMT) signalingdimensions.
 6. The apparatus of claim 1, wherein: the plurality oforthogonal signaling dimensions includes a plurality of unusedorthogonal signaling dimensions and plurality of permitted orthogonalsignaling dimensions; and the apparatus is operative to performinterference cancellation within the received information using theplurality of unused orthogonal signaling dimensions.
 7. The apparatus ofclaim 1, wherein: the plurality of orthogonal signaling dimensionsincludes a plurality of unused orthogonal signaling dimensions andplurality of permitted orthogonal signaling dimensions; a modificationof the power per orthogonal signaling dimension for the at least one ofthe plurality of orthogonal signaling dimensions is a modification froma first power per orthogonal signaling dimension to a second power perorthogonal signaling dimension; a ratio of the first power perorthogonal signaling dimension over the second power per orthogonalsignaling dimension is at least one of: an inverse of a ratio of anumber of orthogonal signaling dimensions within the plurality oforthogonal signaling dimensions over a number of permitted orthogonalsignaling dimensions within the plurality of permitted orthogonalsignaling dimensions; and a ratio of the number of permitted orthogonalsignaling dimensions within the plurality of permitted orthogonalsignaling dimensions over the number of orthogonal signaling dimensionwithin the plurality of orthogonal signaling dimensions.
 8. Theapparatus of claim 1, wherein: the communication channel includes aspectrum portion that is partitioned into a plurality of logicalchannels; and the apparatus simultaneously receives the informationtransmitted from the transmitting apparatus via at least two of theplurality of logical channels.
 9. The apparatus of claim 1, wherein: theapparatus is a cellular communication device that is operative within acellular communication system.
 10. The apparatus of claim 9, wherein:the cellular communication system is a bi-directional cellularcommunication system.
 11. A cellular communication device, comprising: areceiver module that is operative to receive information transmittedfrom at least one additional cellular communication device using aplurality of orthogonal signaling dimensions via a communicationchannel; and a transmission instruction module that is operative togenerate a control signal, based upon the received information, that iseffective to instruct the at least one additional cellular communicationto modify at least one of: a number of orthogonal signaling dimensionswithin the plurality of orthogonal signaling dimensions employed for asubsequent transmission there from; and a power per orthogonal signalingdimension for at least one of the plurality of orthogonal signalingdimensions for the subsequent transmission there from; and wherein: thecellular communication system is a bi-directional cellular communicationsystem.
 12. The cellular communication device of claim 11, wherein: amodification of the number of orthogonal signaling dimensions within theplurality of orthogonal signaling dimensions is a reduction in thenumber of orthogonal signaling dimensions within the plurality oforthogonal signaling dimensions to a plurality of permitted orthogonalsignaling dimensions.
 13. The cellular communication device of claim 11,wherein: a modification of the power per orthogonal signaling dimensionfor the at least one of the plurality of orthogonal signaling dimensionsis an increase of the power per orthogonal signaling dimension.
 14. Thecellular communication device of claim 13, wherein: a first power perorthogonal signaling dimension corresponding to a first of the pluralityof orthogonal signaling dimensions is increased by a first amount; and asecond power per orthogonal signaling dimension corresponding to asecond of the plurality of orthogonal signaling dimensions is increasedby a second amount.
 15. The cellular communication device of claim 11,wherein: the plurality of orthogonal signaling dimensions is a pluralityof code division multiple access (CDMA) signaling dimensions, aplurality of synchronous code division multiple access (S-CDMA)signaling dimensions, a plurality of time division multiple access(TDMA) signaling dimensions, a plurality of orthogonal frequencydivision multiplexing (OFDM) signaling dimensions, or a plurality ofdiscrete multi-tone (DMT) signaling dimensions.
 16. The cellularcommunication device of claim 11, wherein: the plurality of orthogonalsignaling dimensions includes a plurality of unused orthogonal signalingdimensions and plurality of permitted orthogonal signaling dimensions;and the apparatus is operative to perform interference cancellationwithin the received information using the plurality of unused orthogonalsignaling dimensions.
 17. The cellular communication device of claim 11,wherein: the plurality of orthogonal signaling dimensions includes aplurality of unused orthogonal signaling dimensions and plurality ofpermitted orthogonal signaling dimensions; a modification of the powerper orthogonal signaling dimension for the at least one of the pluralityof orthogonal signaling dimensions is a modification from a first powerper orthogonal signaling dimension to a second power per orthogonalsignaling dimension; a ratio of the first power per orthogonal signalingdimension over the second power per orthogonal signaling dimension is atleast one of: an inverse of a ratio of a number of orthogonal signalingdimensions within the plurality of orthogonal signaling dimensions overa number of permitted orthogonal signaling dimensions within theplurality of permitted orthogonal signaling dimensions; and a ratio ofthe number of permitted orthogonal signaling dimensions within theplurality of permitted orthogonal signaling dimensions over the numberof orthogonal signaling dimension within the plurality of orthogonalsignaling dimensions.
 18. A method, comprising: employing acommunication device to receive information transmitted from at leastone additional communication device using a plurality of orthogonalsignaling dimensions via a communication channel; and based upon thereceived information, generating a control signal effective to instructthe at least one additional communication device to perform at least oneof: modifying a number of orthogonal signaling dimensions within theplurality of orthogonal signaling dimensions employed for a subsequenttransmission there from; and modifying a power per orthogonal signalingdimension for at least one of the plurality of orthogonal signalingdimensions for the subsequent transmission there from.
 19. The method ofclaim 18, wherein: a modification of the number of orthogonal signalingdimensions within the plurality of orthogonal signaling dimensions is areduction in the number of orthogonal signaling dimensions within theplurality of orthogonal signaling dimensions to a plurality of permittedorthogonal signaling dimensions; and a modification of the power perorthogonal signaling dimension for the at least one of the plurality oforthogonal signaling dimensions is an increase of the power perorthogonal signaling dimension.
 20. The method of claim 18, wherein: theplurality of orthogonal signaling dimensions is a plurality of codedivision multiple access (CDMA) signaling dimensions, a plurality ofsynchronous code division multiple access (S-CDMA) signaling dimensions,a plurality of time division multiple access (TDMA) signalingdimensions, a plurality of orthogonal frequency division multiplexing(OFDM) signaling dimensions, or a plurality of discrete multi-tone (DMT)signaling dimensions.